Malodors reduction

ABSTRACT

The invention concerns a method of reducing the organoleptic effect of undesirable aldehydic components in a triglyceride or derivative thereof by addition of a reaction product of an amine and an organoleptically acceptable aldehyde. The triglyceride may be a food or food component such as an edible fat or a surface active agent such as a detergent. The reaction product may be incorporated in the perfume or flavor to be added to the triglyceride or derivative thereof without distorting their organoleptic effect.

This is a continuation of application No. 07/507,833, filed on Apr. 12,1990, which was abandoned upon the filing hereof.

FIELD OF THE INVENTION

This invention relates to a method for removing or reducing unpleasantmalodors or off-flavors arising from the presence of aldehydic materialsin fats, oils and related products.

BACKGROUND TO THE INVENTION

Fats and oils are complex water insoluble substances derived from animalor vegetable sources and comprised of a large number of organicmaterials. The major components are glyceryl esters of fatty acids,particularly triglyceryl esters derived from lauric, myristic, palmitic,stearic, erucic, oleic, linoleic and linolenic acids. Traditionally,oils are distinguished from fats only in that they are liquid at roomtemperature, and for convenience, the term `fats` as used hereafter willbe assumed to refer equally to oils.

Commercial exploitation of fats is extensive. Millions of tons of fatsare directly used per annum in edible products, the most important ofwhich are butter, margarine, lard, shortening, mayonnaise, salad oil andcooking oil. Large quantities of fat are also used directly in non-foodproducts, for example, in grease and lubricants, in cosmetics, and inpaints and varnishes (as `drying oils`) In addition, fats are valuableraw materials in the chemicals industry as major sources of fatty acidsand their derivatives, among which particular mention should be made ofsalts, esters, alcohols, amides and other nitrogen derivatives.Manufactured products which commonly incorporate fatty acids or fattyacid derivatives are soaps, plasticisers, polymers, rubber tyres,cosmetics and alkyd resins.

A large proportion of the non-food consumption of fats is accounted forby the production of surface active agents for use as detergents,cleansers and emulsifiers. Among the most important surface activeagents are soaps, i.e. salts of fatty acids with sodium, potassium orother metal cations, or with non-metallic cations such as thosecontaining a quadrivalent nitrogen atom. Many other classes of fattyacid-based surface active agents e.g. fat derived surfactants includingsecondary alkane suphonates, alcohol sulphates, ethoxylated fattyalcohol sulphates, mono and dialkanolamides and alkanolamide sulphates,fatty alcohol ethoxylates, polyethoxylated fatty acid esters,ethoxylated alkanolamides; cationics (particularly quarternary ammoniumcompounds); amine oxides, ethoxylated derivatives of amine oxides, andamphoterics and sorbitan esters are known and utilised in the syntheticdetergent industry.

Glyceride derived emulsifiers are used in the food industry and thepresent invention relates to them also Examples are mono-/di-glyceridesand their esters with lactic acid, citric acid, acetic anhydride anddiacetyltartaric acid; stearoyl lactylates; fatty acid esters ofsucrose, sorbitol, propylene glycol and polyglycerol; poly (fatty acid)esters of polyglycerol.

A problem feature of many of the above mentioned products arises fromthe occurrence in fats of materials which are odoriferous and which havethe potential to adversely affect products' odor properties, and also,by extension to the edible products area, the perception of taste, sincethis is influenced by both flavor and odor. The magnitude of the problemis generally difficult to gauge since the occurrence of the odoriferousmaterials is dependent on many factors such as type of constituent fats,geographical source, chemical and thermal history of the fats, storageconditions, age of product, and presence or absence of preservatives andanti-oxidants. Often, several of these factors may vary simultaneouslywith the result that odor problems may occur spasmodically and bedifficult to rationalize. Furthermore, it is clear the intrinsic odorcharacteristics of the product itself, and its intended use, will alsohave a bearing on the required quality of the incorporated fat.

An example of a malodorous material is the unsaturated aldehyde2,4-decadienal which gives a distinctive green note at sub ppb levels.This aldehyde has been detected in the headspace above deteriorated soyabean oil. Other malodour aldehydes are known to be present in fatderived materials, e.g. 2,4-dodecadienal.

GENERAL DESCRIPTION OF THE INVENTION

It is the aim of the present invention to reduce such problems by theaddition of flavors or fragrances which are robust in action, and areunusual in that they possess not only perfumery or flavor componentscapable of eliciting pleasant sensory responses but in addition theyincorporate chemically reactive components which are compatible withfragrances/flavors and whose presence may reduce the concentration ofthe aldehydic materials often associated with rancidity.

The invention provides a method of reducing the organoleptic effect ofan undesirable aldehydic component in a triglyceride or derivativethereof by addition of the product of an amine with an organolepticallyacceptable aldehyde. The product may be incorporated in a fragrance orflavor composition prepared for addition to a triglyceride orderivative.

The term triglyceride and derivative extends to direct derivatives oftriglycerides and compositions containing these materials. Examples aremono- and di-glycerides, glycerol, long chain fatty acids and theirsalts.

A common method of counteracting malodours is to ameliorate theireffects by `odor masking`, i.e. the addition of organolepticallyacceptable materials which act to suppress sensorially the perception ofmalodorants. The method described here, on the other hand, uses reactionproducts of amines and aldhydes with the potential to chemically reducethe concentration of aldehydic malodorants by direct chemical trapping,with comcomitant release of desirable perfume flavor aldehydes into theproduct over time. This represents, in effect, an exchange processreplacing unwanted aldehydes with desirable aldehydes.

A key feature of the invention is the use of chemically reactivemalodour counteractants which may be used in the presence of typicalfragrance, flavor components, without gross distortion of the overallsensory characteristics of the fragrance flavor in the end product.

The malodour counteractants claimed in this invention are compatiblewith fragrances and flavors, but have the potential to produce in situagents with nucleophilic centers which can react readily with compoundscontaining one or more aldehyde groups. An example of such an agent fora particular situation would be an amine with low odor impact and withgood diffusive properties (to facilate permeation within a product). Theamine could be generated within the product via, for example, a iminocompound such as a Schiff's base. These materials are known to exist asequilibrium mixtures of the imine and the precursor compounds, the exactcomposition depending upon factors such as temperature, pH and amount ofwater present.

Whilst the precise mechanism of malodour reduction by the presentinvention is not known it is postulated that when a perfume or flavorincorporating a Schiff's base is added to a product the equilibriumposition is likely to change, and re-equilibration occur, involving theundesired aldehydes present in the product. An exchange of aldehydes maytherefore take place: ##STR1##

Schiff's base are known and utilized in perfumery, but differ from thosedescribed here in that they are generally prepared from amine precursorswhich are themselves known perfumery materials. Scission of such baseswould therefore liberate amino-compounds with high odor impacts, withthe potential to adversely affect the odor characteristics of thefragranced product.

However the use of the reaction products of amines and organolepticallyacceptable aldehydes, usually referred to as Schiff's bases, to reducethe problem of the undesired aldehydic components in triglycerides andderivatives is a novel feature of the present invention.

LITERATURE

Attempts to reduce malodour using chemicals which react with malodorantmaterials are known. However the use of such materials with perfumeswould be deleterious. Thus ozone (used in ventilator systems) wouldoxidize and destroy a large proportion of the terpenoids and unsaturatedmaterials in perfumes. Sodium bisulphite (used in aqueous fish extractsJ Food Sci., 48, 1064 to-1067, 1983) and alkanolamines per se (used incontaminated gas streams Pat. GB 1 596 752/3) would react with mostaldehydes and would distort the odor characteristics of a typicalperfume or flavor. Additionally, in the literature examples, it is thebasicity of the alkanolamines which is exploited in order to reduceacidic malodours through simple acid-base reactions with carboxylicacids such as butyric and phenylacetic acids.

Amines are used to remove aldehydic impurities in a single componentmaterial, acrylic acid, (U.S. Pat. No. 3725208) but this is followed bya distillation stage to separate out the purified acid. Such a processis generally not suitable for the multi-component systems which arefragranced of flavored.

Thus the chemicals used for odor removal in these examples areunsuitable for application in the presence of conventional fragrances orflavors.

COMPONENTS OF THE INVENTION

Examples of the amine and aldehyde components usable in the inventionare:

Amine Components

i) Aminoalkanes of general formula: ##STR2##

ii) Diaminoalkanes of general formula: ##STR3##

iii) Alkanolamines of general formula: ##STR4##

For example, monoethanolamine (i.e. n is 2)

    H.sub.2 NCH.sub.2 CH.sub.2 OH

iii) Phosphatidylethanolamines of the type: ##STR5##

iv) Alpha-amino acid esters of the type:

    H.sub.2 NCH(R'')CO.sub.2 R'

R' is CH₃, Ph, PhCH₂, C2 to C4 straight and branched alkyl groups

R" is H, CH₃ CH₂, CH₃ CH₂ CH(CH₃) (CH₃)₂ CHCH₂, H₂ NCO, HSCH₂ RO₂ CCH₂CH₂, [where R=H,CH₃, CH₃ CH₂ ], CH₃ SCH₂ CH₂, HOCH₂, (CH₃)₂ CH, PhCH₂,p-hydroxyphenylmethyl

For example:

Leucine esters-- ##STR6##

v) Beta-, or gamma-amino acid esters of general formula ##STR7##

These amines are organoleptically acceptable because the balance of theperfume is not disturbed.

Aldehydic Components

i) Alkanals of types: ##STR8##

ii) Unsaturated aldehydes of types:

    ______________________________________                                        a) CH.sub.2 CH(CH.sub.2).sub.n CHO                                                                where n is 6 to 9                                         b) CH.sub.3 (CH.sub.2).sub.m CHCH(CH.sub.2).sub.n CHO                                             m + n is 2 to 8                                           c) Citronellal                                                                d) Phenylpropanals:                                                           R"PhCH.sub.2 CH(R')CHO                                                                            R' is H or CH.sub.3                                                           R" is H, isopropyl,                                                           tert-butyl                                                e) Phenylacetaldehydes:                                                       PhCH(R)CHO          R is H or CH.sub.3                                        f) Cyclohexene carboxaldehydes:                                                ##STR9##           R", R", R" are each H or CH.sub.3                         g) Cinnamic aldehydes:                                                        PhCHCH(R)CHO        R = H, CH.sub.3, pentyl,                                                      hexyl                                                     h) Benzaldehydes:                                                             RPhCHO              R is H, isopropyl, OCH.sub.3                                                  or tertbutyl.                                             i) Hydroxy derivatives of a) to h),                                           for example: Hydroxycitronellal                                               ______________________________________                                    

In the above lists of components Ph is either phenyl or phenylene.

Unsuitable amine components are i) esters of anthranilic acid in whichthe alkyl group of the ester is CH₃, C₂ to C₄ straight and branchedchain alkyl groups, ii) o-amino-acetophenone. The amines are unsuitablebecause (i) and (ii) generally distort the perfume characteristics.

SPECIFICATION DESCRIPTION OF THE INVENTION

Examples 1 and 2 describe the preparation and use of malodourcounteractants based on ethanolamine and on leucine esters. FragrancesF1, F2 and F3 are floral soap perfumes available from QuestInternational UK Ltd.

EXAMPLE 1

A Schiff's base was prepared by adding undecanal dropwise over 1 hour toa stirred solution of 2-methoxyethylamine (equimolar) in ethanol (10%w/w) maintained at 4 to 5° C. The solvent was removed on a rotaryevaporator to yield the expected Schiff's base (I) in 88% purity (byglc).

    CH.sub.3 (CH.sub.2).sub.9 CH═N--(CH.sub.2).sub.2 OCH.sub.3(I)

This material was incorporated at several concentrations into soapperfume F1 which was used to fragrance soap derived from distilled fattyacids. This soap was known to contain unsaturated aldehydes, inparticular 2,4-decadienal, by gc/ms analysis of the materials present inits headspace, i.e. air in contact with the soap. The odor character ofthe soap was distinctive, and its fatty, linseed-like notes were foundto adversely affect perfume performance (for normal perfume loadings of0.8% to 1.5% w/w).

Soap bars (ca 75g) incorporating 1.2% by weight of perfume, with andwithout additive, were prepared by conventional milling, plodding andstamping. These bars were stored at 37° C. for 1 month prior toolfactory assessment by a sensory panel trained in the method ofMagnitude Estimation (ME). The sensory results given in Table 1 suggestthat perfume performance, as indicated by perceived perfume intensity,was enhanced in samples containing Product (I).

The observed improvement in perfume performance may be interpreted asarising from an effect on the malodour itself. Standard statisticaltests (triangle tests) on samples of the perfume with/without product Ishowed that the presence of product I had no effect on the sensorycharacteristics of the fragrance.

                  TABLE 1                                                         ______________________________________                                        Perceived Perfume Intensities (ME) of Soap Bars                               Incorporating Perfume F1 with and without Product (I).                                      Perceived Perfume                                               % Product (I)*                                                                              Intensity**                                                     ______________________________________                                        0             37.7                                                            0.25          39.5                                                            0.50          41.1                                                            1.00          53.3                                                            ______________________________________                                         *w/w Relative to the perfume                                                  **Arbitrary units (magnitude estimates)                                  

EXAMPLE 2

Product (II) was prepared from an equimolar mixture of leucine ethylester free base (6.5g, obtained from the hydrochloride salt ex Sigma)and dodecanal, in toluene as solvent. Water was removed by azeotropicdistillation and, on cooling, the mixture was washed successively withdilute acid, bicarbonate solution and finally brine. Removal of toluenegave 10.5 g of a yellow material, Product (II).

Soap bars were made up as in Example 1, but using perfume F1 or F2with/without additive. For comparison, ethyl leucine free base wasitself included as an additive in the test. Storage conditions were asabove, but odor assessment was carried out by an expert panel.

The results in Table 2 show soap bars which contained perfumeincorporating malodour counteractant Product II achieved lower scoresthan did other soap bars, i.e. were preferred on average. It isinstructive to note soap bars containing leucine ethyl ester free base,which has the potential to scavenge aldehydes directly, in fact scoredworse than the control bars (with unmodified perfume) in three out offour cases.

                  TABLE 2                                                         ______________________________________                                        Odour Assessments of DFA Soap Bars Incorporating                              Perfume with/without Malodour Counteractants.                                 Perfume  Additive    % Additive  Rank Sum                                     ______________________________________                                        F1       None        0.00        11                                                    LE          0.50         8                                                    LE          2.00        15                                                    Product II  0.50         6                                                    Product II  2.00         5                                           F2       None        0.00        10                                                    LE          0.50        14                                                    LE          2.00        12                                                    Product II  0.50         3                                                    Product II  2.00         6                                           ______________________________________                                         Notes:                                                                        a) LE is leucine ethyl ester (free base)                                      b) % Additive is relative to perfume                                          c) Rank sum  obtained from two perfumers and one fragrance evaluator usin     a scale 1 = best to 5 = worst.                                           

EXAMPLE 3

Materials used in this example were:

    ______________________________________                                        Flavor      coconut-flavor composition taken from                                         the "Source Book of Flavors", AVI                                             Publishers (1981), flavor code MF89                                           page 731                                                          Malodour:   2,4-dodecadienal                                                  Counteractants:                                                                           a) 2-methoxyethylamine/undecanal                                              reaction product (I)                                                          b) Leucine ethyl ester/dodecanal                                              reaction product (II)                                             ______________________________________                                    

The dienal was added (0.5%) to the coconut flavor composition (0.5%) todistort its flavor character with an off-note typical of degraded fats.The effectiveness of additives (I) and (II) in reducing the perceivedintensity of the off-note, and restoring the original coconut characterwas then assessed sensorially for two systems dosed with 750 ppm of theflavor i.e. an oil in water emulsion, and a liqueur-type alcoholicsolution.

After storage for one week the flavor with/without additives was takenup in the emulsion (prepared from ICI Speciality Chemicals HLB 10mixture, at 10%, and Huile d'Avocat at 2%), and compared olfactoriallywith a standard (the untainted flavor) using an ordinal scalingtechnique. A similar experiment was carried out using the liqueursamples (made up with 25% alcohol and 23% sucrose).

The sensory results obtained from 10 panellists are summarized in Table3.

                  TABLE 3                                                         ______________________________________                                        Olfactory assessment of liquids incorporating a                               tainted coconut flavor                                                                   Average                                                                       Score**                                                            Sample*      EMULSION    ALCOHOLIC SOLN.                                      ______________________________________                                        Flavor + dienal                                                                            2.65        2.7                                                  Flavor + dienal +                                                                          1.9         1.0                                                  (I) at 1%                                                                     Flavor + dienal +                                                                          1.45        2.3                                                  (II) at 1%                                                                    ______________________________________                                         *dienal incorporated into the flavor at 0.5%                                  **10 panellists, using a scale 1 = best (most true to original flavor) 3      worst                                                                    

Samples containing products (I) and (II) achieved better scores than thetainted sample of the oil-in-water emulsion suggesting, that aldehydicmalodour has been reduced. Trials using the additives in the absence ofdienal did not reveal any significant differences between samples.

In the case of the alcoholic solutions the aldehydic malodour was muchmore prominent and a marked odor improvement was observed for samplesincorporating additive (I).

EXAMPLE 4

Product (III) was prepared from the aldehyde 3-(4-tert.butylphenyl)-2-methylpropanal and 2-aminoethanol as follows:

The aldehyde (50 ml) was placed in a round-bottomed flask and to it wasadded 2-aminoethanol (12.5 ml) in ca. 1 ml portions with stirring.

The samples were dehydrated with anhydrous sodium sulphate (excessrelative to the amount of water produced) and finally filtered throughphase separation filter paper before dilution and use.

GC/MS data indicated that the major product of the reaction was anadduct of the aldehyde and the amine.

EXAMPLE 5

Product (IV) was prepared from the aldehyde4-(4-methyl-4-hydroxypentyl)-3-cyclohexenecarboxaldehyde and2-aminoethanol as follows:

The aldehyde (50 ml) was placed in a round-bottomed flask and to it wasadded 2-aminoethanol (12.7 ml) in ca. 1 ml portions with stirring.

Workup was as in Example 4. GC/MS data indicated that the major productof the reaction was an adduct of the aldehyde and the amine.

EXAMPLE 6

Product (V) was prepared from 3-(4-tert. butylphenyl)-2-methylpropanaland 1,2-diaminoethane as follows:

The aldehyde (10.2g) was placed in a round-bottomed flask and to it wasadded 1,2-diaminoethane (1,43g) with stirring.

The reaction product was filtered through phase separation paper andused without further treatment.

Spectroscopic date (¹³ C/¹ H NMR) of the reaction product was consistentwith a mixture of the imine (1.1 adduct), the diimine (amine: aldehyde1:2 adduct) and excess aldehyde.

EXAMPLE 7

Products (III), (IV) and (V) were incorporated separately into perfumeF3 at a level of 0.5% w/w. Soap bars fragranced with F3 or itsmodifications were made up as described in Example 1, but using astandard high quality super-fatted soap base which had previously beendosed with 2,4-decadienal (a malodorant aldehyde) at a concentration of50 ppm.

Following storage at 37° C. for 10 days, the soap bars were evaluatedfor olfactory performance by a panel of experts.

The sensory results given in Table 4 show that the bars containingperfumes incorporating the malodour counteractants achieved betterscores than those containing the unmodified perfume.

                  TABLE 4                                                         ______________________________________                                        Odor Assessments of Malodorous Soap Bars incorporating                        Perfume with/without Malodour Counteractants.                                 Perfume                                                                              Counteractant                                                                              % Counteractant                                                                             Rank Sum                                    ______________________________________                                        F3     None         0.00          16.0                                               Product (III)                                                                              0.50          11.0                                               Product (IV) 0.50           7.0                                               Product (V)  0.50           6.0                                        ______________________________________                                         Notes:                                                                        a) % Counteractant is w/w relative to the perfume                             b) Rank sums were obtained from 4 assessors using a scale 1 = best to 4 =     worst.                                                                   

We claim:
 1. A method of reducing the organoleptic effect of undesirablealdehydic components in triglycerides or derivatives thereof bychemically trapping the aldehydic component with a reaction product ofan organoleptically acceptable aldehyde and an amine chosen fromi)Aminoalkanes of general formula: ##STR10## ii) Diaminoalkanes of generalformula: ##STR11## Alkanolamines of general formula: (NH₂) (C_(n)H_(2n)) (OH), where n is a maximum of 10, and their alkyl and(poly)oxyethylene ether derivatives, Phosphatidylethanolamines of thetype: ##STR12## iv) Alpha-amino acid esters of the type:

    H.sub.2 NCH(R")CO.sub.2 R'

R' is CH₃, Ph, PhCH₂, C₂ to C₄ straight and branched alkyl groups, R" isH, CH₃ CH₂, CH₃ CH₂ CH(CH₃), (CH₃)₂ CHCH₂, H₂ NCO, HSCH₂, RO₂ CCH₂ CH₂,CH₃ SCH₂ CH₂, HOCH₂, (CH₃)₂ CH, PhCH₂, p-hydroxphenylmethyl, v) Beta-,or gamma-amino acid esters of general formula: ##STR13##
 2. A methodaccording to claim 1 wherein the aldehyde is chosen from:i) Alkanals oftypes: ##STR14## ii) Unsaturated aldehydes of types:

    ______________________________________                                        a) CH.sub.2 CH(CH.sub.2).sub.n CHO                                                                where n is 6 to 9                                         b) CH.sub.3 (CH.sub.2).sub.m CHCH(CH.sub.2).sub.n CHO                                             m + n is 2 to 8                                           c) Citronellal                                                                d) Phenylpropanals:                                                           R"PhCH.sub.2 CH(R')CHO                                                                            R' is H or CH.sub.3                                                           R" is H, isopropyl,                                                           tert-butyl                                                e) Phenylacetaldehydes:                                                       PhCH(R)CHO          R is H or CH.sub.3                                        f) Cyclohexene carboxaldehydes:                                                ##STR15##          R", R", R" are each H or CH.sub.3                         g) Cinnamic aldehydes:                                                        PhCHCH(R)CHO        R = H, CH.sub.3, pentyl,                                                      hexyl                                                     h) Benzaldehydes:                                                             RPhCHO              R is H, isopropyl, OCH.sub.3                                                  or tertbutyl,                                             i) Hydroxy derivatives of a) to h).                                           ______________________________________                                    


3. A method according to claim 1, wherein the triglyceride derivative isa soap.